Avian Metapneumovirus Infection Rhinotracheitis (Swollen Head Syndrome SHD) in Laying Hens
Happenings / Clinical Signs
Visibly sick birds
- Few visibly sick birds
- Usually less than 4% of the flock are affected
Egg drop
- Egg production may be affected
- Egg production drop gradually
Mortality
- Low mortality or increases gradually
- Mortality rarely exceeds 2%
Dead Birds
- Poor body fleshing condition
Head Comb Wattles Face Nostrils Sinuses Mount Beak Ear lobes
- Swelling of the Head
- Swelling of the periorbital and infraorbital sinuses
Respiratory
- Respiratory signs spread fast
- Widespread respiratory signs are usually present
Neurological /Nervous
As a result of secondary E. coli infection
- Torticollis
- Cerebral disorientation
- Opisthotonus
Neck wings breast abdomen shanks legs hocks feet joints vent skin
- Hens in lay may also present with prolapsed oviducts due to violent coughing
Shell quality
- Pale or loss of colour in brown-shelled eggs
- Misshapen eggs
The Avian metapneumovirus infection has been associated with swollen head syndrome (SHS) in chickens, which is characterized by the following clinical signs: swelling of the periorbital and infra-orbital sinuses, torticollis, cerebral disorientation and opisthotonus, as a result of secondary E coli infection. Usually less than 4% of the flock are affected, although, widespread respiratory signs are usually present. Mortality rarely exceeds 2%. The infection is associated with reduced egg production loss the shell colour and misshapen eggs.
- Causing Agents
- Avian metapneumovirus infection. Avian Metapneumoviruses are members of the subfamily Pneumoviridae, belonging to the family Paramixoviridae
- Affected Systems/Organs
- Respiratory, Reproductive and Neurological System
- Spread
- Transmission is rapid through aerosols via the respiratory route. Transmission from parents is uncertain. Contaminated objects.
- Mainly Affects
- Egg production, Egg quality and Liveability
- Solution
- Control respiratory stressors. Multivitamins. Good management practices. Good biosecurity.
- Suggested Actions
- Can be confirmed with clinical signs and gross lesions
- Can be managed with feed additives, off-the-shelf medications
- Diagnosis should be confirmed with rapid assays and/or a certified laboratory
- Veterinary intervention is recommended
Impact on Egg quality

Impact on Liveability

Impact on Production

Overall Economic Impact

Y.M. Saif.2008.Disease of Poultry. 12th Edition. page 113
David E. Swayne. 2013. Diseases of Poultry 13th Edition. page 115
Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition.
Paul McMullin. 2004. A pocket Guide to Poultry Health and Disease. First Edition.
Steven Leeson, John D. Summers. 2008. Commercial Poultry Nutrition. Third Edition.
Donald D. Bell, Williams D. Weaver. 2009. Commercial Chicken Meat and Egg Production. Fifth Edition.